Method for exchanging information between devices in case of a change in network configuration and home network system therefore

ABSTRACT

A method for exchanging information between appliances to notify a home server of a network configuration change and a home network system therefore is disclosed. In the present invention, when an electronic appliance is connected to a network, the appliance first transmits a particular message to a home server N (&gt;1) times at interval of a first period and then transmits the particular message periodically at interval of a second period which is longer than the first period, thereby letting the homer server know which appliances are connected to the network in real-time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for exchanging informationbetween electronic appliances for notifying a managing appliance ofnetwork configuration changes and a home network system therefor.

b 2. Description of the Related Art

In a home network system as shown in FIG. 1 wherein a home server and aplurality of electronic appliances are connected through a network N, anarbitrary electronic appliance can be monitored and controlled throughthe network N.

In the home network system, a plurality of electronic appliances C1through C4 such as washing machines or microwave ovens are connected toa home server appliance such as a refrigerator having built-in homeserver functionality. The manager of the home network system can controland monitor the plurality of electronic appliances connected to the homenetwork in a centralized way by transmitting control commands to theplurality of electronic appliances and receiving information about theexecution results of the control commands through a different applianceconnected to the network such as a PC or a PDA.

When an electronic appliance is newly connected to the home network, theappliance is assigned a unique network address by the home server andbecomes on-lined to the network. While an electronic appliance ison-lined to the network, the appliance can provide status information tothe home server and respond to monitoring/control messages from the homeserver.

The home server maintains the appliances that are in on-line asconnected appliances. The power to an on-lined appliance may be turnedoff abruptly by a user or the physical connection between the applianceand the network may get broken. In this case, the home server should beable to detect such conditions. Otherwise, the home server may providewrong information to the user of the network and therefore the user mayissue wrong control commands based on the wrong information.

SUMMARY OF THE INVENTION

In view of the shortcomings of the prior art, it is an object of thepresent invention to provide a home network system that is capable ofmonitoring the status of the devices connected to the network inreal-time and thus allows reliable management of the devices and amethod therefore.

In the present invention, an electronic device transmits a particularmessage to a managing device periodically to inform that the device ison-lined or transmits a message for connection close according to user'srequest.

In one embodiment of the present invention, when a device is connectedto the network, the device transmits the particular message to themanaging device N times at interval of a first period and thenrepeatedly at interval of a second period longer than the first period.

In one embodiment, if the managing device does not receive theparticular message during the interval of the second period, themanaging device transmits a message requesting a reply to the device anddetermines the status thereof based on the result.

In one embodiment, if it is determined that the device is off-lined, themanaging device reduces management information for the device.

In one embodiment, if it is determined that the device is off-line, themanaging device moves the information about the device from theinformation area for on-lined devices to the information area foroff-lined devices after deleting information about the operation of thedevice.

In another embodiment of the present invention, the managing deviceregards a device that transmitted a connection close message as beingoff-lined and reduces management information for the device.

In another embodiment, if a command for monitoring or controlling thedevice regarded as off-lined is received, the command is not executed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and other advantages of the present invention will bemore clearly understood from the following detailed description taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a typical home network system established in a house;

FIG. 2 illustrates exemplary components constituting a home network;

FIGS. 3 a and 3 b illustrate home network systems in which the presentinvention may be advantageously embodied;

FIG. 4 illustrates a flow chart of the method for exchanging informationbetween devices in accordance with a first embodiment of the presentinvention; and

FIG. 5 illustrates a flow chart of the method for exchanging informationbetween devices in accordance with a second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order that the invention may be fully understood, preferredembodiments thereof will now be described with reference to theaccompanying drawings.

FIG. 2 illustrates a detailed schematic diagram of a managing device ina home network system. FIGS. 3 a and 3 b illustrate home network systemsin which the present invention may be advantageously embodied.

A network manager 100 is a home server that controls signals exchangedbetween a plurality of electronic appliances connected to the network Nand manages information for communication with other networks such asthe Internet. In the preferred embodiments of the present invention, thenetwork manager is built into a refrigerator that is powered all daylong.

Also, the network manager 100 stores and manages network allocationinformation for network connection, operation status, and detailedsetting for operation of each of the plurality of devices such aselectronic appliances.

As shown in FIG. 2, the network manager 100 comprises a control unit130, a database 140, and a communication module 150. The control unit130 generates control commands for controlling the operation of each ofdevices 200 _(I) connected to the network N. If the control unit 130receives a message for connection close from a device or fails todetects a device on the network under the condition that it has notreceived an “alive” message during a predefined period of time from thedevice, the control unit 130 removes or modifies information about thedevice. The database 140 stores information about devices that are orwere connected to the network N. The communication module 150 transmitsand receives data through the network N.

The control unit 130 comprises a timer 131 for counting down a timeoutvalue set by each of the devices 200 _(I), a control module 132, and aconnection status monitoring module 133. If a timeout value that was setby one of the devices 200 _(I) expires, the connection status monitoringmodule 133 monitors the connection status of the device. If a messageindicative of connection close is received from a device or theconnection status monitoring module 133 determines that a device is notfound, the control module 132 regards the device as being off-lined andmanages the device accordingly. The control module 132 regards devicesthat have transmitted the “alive” message on a regular basis as beingon-line. Also, the control module 132 performs status monitoring orissues control signals according to user's request.

The type of the communication module 150 depends on the physical mediaused in constructing the network N. The communication module 150 is apower line modem in a power line network as shown in FIG. 3 b and is awireless modem in a wireless network. The communication module 150 isdetermined by what type of physical media is used.

The network manager 100 may further comprise an output unit 120 foroutputting network status information and control results in response tocontrol signals from the control unit 130. The output unit 120 can bebuilt into a single panel with an input unit 110 for providing moreconvenient user interface.

Each of the devices 200 _(I) comprises a control unit 230 and acommunication module 250. The control unit 230 generates control signalsfor controlling components of the device in response to control commandsreceived from the network manager 100 and transmits the “alive” messageindicating that the device is on-lined to the network managerperiodically at predefined intervals. Also, the control module 230issues a message indicative of connection close when a special requestis received from a user. The communication module 250 performs datacommunication through the network N.

Like the communication module 150 of the network manager 100, the typeof the communication module 250 depends on the type of the media. Thecommunication module 250 is a power line modem in case of a power linenetwork and is a wireless modem in case of a wireless network.

When a device that has not been assigned a network address is connectedto the network N, the device requests the network manager 100 to assignit a logical address. If a logical address is assigned by the networkmanager 100, the device generates a network address by combining thelogical address with its own product code and sets the generated networkaddress in the control unit 230 or the communication module 250. Whenassigning the logical address to the device, the network manager 100adds the device to a table of on-lined devices and records networkconfiguration information about the device. When operation status andinformation about the device is obtained afterwards, the network manager100 records the obtained information in the information areacorresponding to the device in the table of on-lined devices.

If a device was connected to the network N once and connected to thenetwork again, the device already has a network address. In this case,the device transmits the “alive” message to the network manager 100without performing the steps to get a logical address.

The “alive” message is transmitted to the network manager 100periodically at short intervals at first and then at long intervals(AliveInt). For example, the “alive” message is transmitted twice atinterval of 5 seconds and then transmitted at interval of 10 minutes. Tonotify the network manager 100 of the period of “alive” message, thedevice transmits the interval between “alive” messages, i.e., AliveInt,to the network manager 100.

Receiving the “alive” message through the communication module 150, thenetwork manager 100 searches the database 140 for information about thedevice that transmitted the “alive” message. If the information aboutthe device is found in the table of on-lined devices, the networkmanager 100 leaves it as it is. If the information is found in the tableof off-lined devices, the network manager 100 moves the information tothe table of on-lined devices. It is also possible to change the statusof the device from ‘off-lined’ to ‘on-lined’ instead of moving theinformation. It is desirable, however, to manage information foron-lined devices and information for off-lined devices separately in thedatabase 140 in that on-lined devices require more information thanoff-lined devices.

Receiving the period of the “alive” message (AliveInt) from a device,the control module 132 records a timeout value for the device in theinformation for the device. The timeout value is set to a value longerthan the received period (e.g., 1.5×AliveInt or 2×AliveInt). Each timean “alive” message is received from a device, the control module 132loads the timeout value associated with the device to the timer 131. Thetimer 131, which has only one clock source, counts down a plurality oftimeout values at each clock tick to check if at least one timeout eventoccurs.

If the information on a device that transmitted the “alive” message isnot found in the database 140, it means that the device has beenconnected to another network and moved to the network N without removingits network address. In this case, the control module 132 executes stepsfor clearing the network address and assigning a new address to thedevice.

If one of the timeout values set in the timer 131 of the network manager100 reaches 0, it means that the “alive” message has not been receivedfrom the device which loaded the timeout value to the timer 131. In thiscase, the control module 132 requests the connection status monitoringmodule 133 to examine if the device exists on the network N.

Even when the device is connected to the network N, the “alive” messagetransmitted by the device may not reach the network manager 100 beforethe preset timeout expires because of excessive network load orinstantaneous signal interference. This is why the examination isneeded.

In summary, even though the “alive” message has not been received from adevice during its preset timeout interval, the network manager 100 doesnot change information on the device immediately and examines if thedevice is connected to the network N through the connection statusmonitoring module 133.

To determine if the device exists on the network N, the connectionstatus monitoring module 133 transmits a message requesting information(e.g., address) to the network N. In the case where the device ison-lined to the network N, the device receives the message and repliesto the message by transmitting a message delivering its address.Receiving the message, the connection status monitoring module 133notifies the control module 132 of the status so that the control module132 keeps the information on the device unchanged.

If the device is off-line, e.g., connection is closed or power is turnedoff, the connection status monitoring module 133 cannot receive a replyto the message requesting address information.

As a result, the control module 132 of the network manager 100 moves theinformation on the device, which is currently included in the table ofon-lined devices, to the table of off-lined devices in the database 140.In this case, information unnecessary in the table of off-lined devices(e.g., current function, status information, operation mode, etc) isremoved. In the case where information should be minimized, allinformation except for the address of the off-lined device can bedeleted when the information is moved to the table of off-lined devices.

Some devices are equipped with the functionality to request connectionclose. If the user of such a device requests connection close, thedevice transmits a message for connection close to the network manager100. Receiving the message for connection close through the network N,the network manager 100 handles the information about the device thattransmitted the message in much the same way as the information aboutthe device that is not detected by the connection status monitoringmodule 133.

Because the network manager 100 monitors the status and configuration ofthe network N in real-time as described before, the network manager 100can reply to user's requests or commands reliably.

If the network manager 100 has the output unit 120, the network manager100 can display which devices are currently on-lined to the network N sothat the user can easily monitor the network status. If the user issuesa command or a request to an off-lined device through the networkmanager 100, the network manager 100 does not perform the command orrequest based on the database 140 thereof. The network manager 100 mayinform the user of the status of the off-lined device.

A user issues control commands or requests through a device havinguser-friendly interface such as a PC, a notebook computer, or a PDA.Such a device is called a master device. Application programs formonitoring and controlling devices connected to the network are executedon the master device. Though the master device performs similarfunctions as the home server, the master device cannot assign logicaladdresses to devices connected to the network and does not supportcommunication with other networks.

Because the master device should know the status and configuration ofthe network N in real-time to manage user's requests properly, themaster device should have information table for devices that arecurrently connected or were connected to the network.

When the network manager 100 updates the database 140 thereof afterdetecting a change in the network configuration, the network manager 100notifies the master device of the change so that the network manager 100and the master device can synchronize databases. Likewise, if the masterdevice detects a change in the network configuration first, the masterdevice needs to notify the network manager 100 of the change. It alsoholds when there are more than one network manger on the network.

In a home network based on the wireless network as shown in FIG. 3 a orbased on the power line network as shown in FIG. 3 b, if a home server101 has not received the “alive” message from a device during its presetperiod of time, the home server 101 examines if the device is still inon-line to the network. If the home server 101 fails to receive aresponse from the device, the home server 101 moves information aboutthe device from the table of on-lined devices to the table of off-lineddevices and deletes unnecessary information.

FIG. 4 illustrates a flow chart of the method for exchanging informationbetween devices in case of a configuration change in a home network inaccordance with a first embodiment of the present invention.

An electronic appliance that is newly connected to the network isassigned a network address by the network manager if necessary andtransmits the “alive” message and its own period of the “alive” messageto the network manager to inform the network manager that the applianceis on line (S1). The appliance transmits the “alive” message N times(e.g., twice) at short intervals at first and then at long intervals.Receiving the “alive” message, the network manager records informationabout the appliance in the table of on-lined devices, if the applianceis assigned a new network address. If the appliance already has anetwork address, the network manager removes information about theappliance from the table of off-lined devices and records necessaryinformation in the table of on-lined devices.

If the “alive” message has not been received during a time intervallonger than the predefined period (e.g., 1.5˜2 times as long as theperiod) (S2), the network manager examines if the device exists on thenetwork (S3).

If the device is not found on the network (S4), the network managermoves the information about the device from the table of on-lineddevices to the table of off-lined devices (S5), in which case only theinformation irrelevant to the operation mode is moved and unnecessaryinformation is deleted. If the device is found (S4), the network managermaintains the information about the device unchanged. Afterwards, thenetwork manager waits for the “alive” message (S7).

FIG. 4 illustrates a flow chart of the method for exchanging informationbetween devices in case of a configuration change in a home network inaccordance with a second embodiment of the present invention. In thisembodiment, an electronic appliance notifies the network manager of itsstatus change from on-lined to off-lined.

If requested by the user, the appliance transmits a message forconnection close to the network manager (S11). Receiving the message,the network manager deletes dynamic information about the appliance andmoves only static information about the appliance to the table ofoff-lined devices (S12). In this case, even though the appliance isphysically connected to the network, the appliance is consideredoff-lined (S13). Afterwards, the user removes the appliance from thenetwork.

The home network system and the method therefore is capable ofmonitoring the status of appliances connected to a network in real-time,thereby minimizing errors in managing electronic appliances existing onthe network and allowing reliable management of the network system.

While the invention has been disclosed with respect to a limited numberof embodiments, those skilled in the art, having the benefit of thisdisclosure, will appreciate numerous modifications and variationstherefrom. It is intended that all such modifications and variationsfall within the spirit and scope of the invention.

1. A method for exchanging information between devices in case of achange in network configuration, comprising the steps of: (a)transmitting a message of a first type to a managing device N times atinterval of a first period when connected to a network, N being greaterthan 1; and (b) transmitting the message of the first type periodicallyto the managing device at interval of a second period after transmittingthe message N times, the second period being longer than the firstperiod.
 2. The method set forth in claim 1, wherein N=2.
 3. The methodset forth in claim 1, further comprising the step of transmittinginformation about the second period to the managing device.
 4. Themethod set forth in claim 1, further comprising the step of obtaining anetwork address by requesting network address assignment to the managingdevice before executing the step (a).
 5. The method set forth in claim1, wherein if the managing device fails to receive a message of thefirst type from a device within the second period, the managing devicetransmits a message of a second type to the device.
 6. The method setforth in claim 5, wherein if there is no acknowledgement to the messageof the second type, the managing device considers the device off-linedand reduces information about the device.
 7. The method set forth inclaim 6, wherein when reducing the information about the device, themanaging device deletes information related to the operation of thedevice.
 8. The method set forth in claim 6, wherein the reducedinformation still contains network address information about the device.9. The method set forth in claim 6, wherein if a command for monitoringor controlling the device considered off-lined is received, the managingdevice provides information indicating that the device is off-lined,without executing the received command.
 10. The method set forth inclaim 1, wherein the first period is 5 seconds and the second period is10 minutes.
 11. A method, performed by a managing device, for managinginformation about devices connected to a network, comprising the stepsof: (a) receiving a connection closing message from a device; and (b)considering the device off-lined and reducing information about thedevice.
 12. The method set forth in claim 11, wherein when reducing theinformation about the device, the managing device deletes informationrelated to the operation of the device.
 13. The method set forth inclaim 11, wherein the reduced information still contains network addressinformation about the device.
 14. The method set forth in claim 11,wherein the device transmits the connection closing message to themanaging device according to user's request.
 15. A network systemthrough which a plurality of devices are connected, comprising: amanaging device for managing information about the plurality of devicesconnected to a network; and a device for transmitting a message of afirst type periodically to the managing device at interval of a secondperiod after transmitting the message of the first type N (N>1) times atinterval of a first period, the second period being longer than thefirst period.
 16. The network system set forth in claim 15, wherein N=2.17. The network system set forth in claim 15, wherein the device obtainsa network address by requesting network address assignment to themanaging device before transmitting the message of the first type. 18.The network system set forth in claim 15, wherein the device provideinformation about the second period to the managing device and themanaging device sets a time limit based on the received second periodand if a message of the first type is not received during the timelimit, the managing device executes steps for detecting the device. 19.The network system set forth in claim 18, wherein the steps fordetecting the device include transmitting a message requesting anacknowledgement and waiting for the acknowledgement.
 20. The networksystem set forth in claim 18, wherein if the device is not detected, themanaging device considers the device off-lined and reduces informationabout the device.
 21. The network system set forth in claim 20, whereinwhen reducing the information about the device, the managing devicedeletes information related to the operation of the device.
 22. Thenetwork system set forth in claim 20, wherein the reduced informationstill contains network address information about the device.
 23. Thenetwork system set forth in claim 20, wherein if a command formonitoring or controlling the device considered off-lined is received,the managing device provides information indicating that the device isoff-lined, without executing the received command.
 24. The networksystem set forth in claim 15, wherein the first period is 5 seconds andthe second period is 10 minutes.
 25. A network system through which aplurality of devices are connected, comprising: a managing device formanaging information about the plurality of devices connected to anetwork; and a device for transmitting a connection closing message tothe managing device if there is a connection release request, wherein ifa connection closing message is received, the managing device reducesinformation about the device which transmitted the message.
 26. Thenetwork system set forth in claim 25, wherein when reducing theinformation about the device, the managing device deletes informationrelated to the operation of the device.
 27. The network system set forthin claim 25, wherein the reduced information still contains networkaddress information about the device.
 28. The network system set forthin claim 25, wherein the connection release request is a command enteredby a user.
 29. An apparatus for managing a device connected through anetwork, comprising: a communication module for transmitting andreceiving data through the network; a database for storing managementinformation including the network address information about the device;a timer for measuring time and detecting timeout of set time limit; anda control unit for reloading the timer with a time limit specified forthe device each time a particular message is received from the devicethrough the communication module, and reducing management informationfor the device as the result of considering the device off-lined if thetime limit specified for the device expires.
 30. The apparatus set forthin claim 29, wherein when reducing the information about the device, thecontrol unit deletes information related to the operation of the device.31. The apparatus set forth in claim 29, wherein the reduced informationstill contains network address information about the device.